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Vector Magnetometry Using the 12-μm Emission Lines

Published online by Cambridge University Press:  03 August 2017

D. Deming ,
T. Hewagama ,
D. E. Jennings ,
G. McCabe  and
G. Wiedemann
D. Deming
Affiliation:
Code 693, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A.
T. Hewagama
Affiliation:
Hughes/STX Corporation, 4400 Forbes Boulevard, Lanham, MD 20706, U.S.A.
D. E. Jennings
Affiliation:
Code 693, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A.
G. McCabe
Affiliation:
Hughes/STX Corporation, 4400 Forbes Boulevard, Lanham, MD 20706, U.S.A.
G. Wiedemann
Affiliation:
European Southern Observatory, Karl-Schwarzschildstrasse 2, D-8046 Garching bei München, Germany

Abstract

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Recent polarimetric observations of the 12.32-μm emission line have provided the observational basis for deriving vector magnetic fields in the upper photosphere with great sensitivity. We use a line source function from the non-LTE model of Carlsson, Rutten and Shchukina, and calculate the radiative transfer of the Stokes I, Q, U, and V profiles. The results show that the profiles are not significantly affected by magneto-optical effects or by saturation, and reliable vector fields can be extracted by simply fitting the Seares relations to the Stokes profiles. Vector field observations for sunspots have shown that the field extends well beyond the photometric boundary of the sunspot, but that the field strength at the penumbral/photospheric boundary is less than half of the sunspot-center value. Within a mature sunspot, the 12-μm line profiles contain essentially no unpolarized radiation, indicating that the field is not intermittent in the sense of containing discrete flux tubes separated by field-free regions. We describe the design of a 12-μm Stokes polarimeter incorporating a high-resolution Fabry-Perot etalon and a 128 × 128 infrared array detector.

Keywords

infrared: starsinstrumentation: polarimetersline formationSun: magnetic fields
Type
Part 5: Magnetic Fields and Infrared Magnetometry
Information
Symposium - International Astronomical Union , Volume 154: Infrared Solar Physics , 1994 , pp. 379 - 392
Copyright
Copyright © Kluwer 1994 

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